Stacked interposer leadframes

ABSTRACT

A stacked leadframe assembly is disclosed. The stacked leadframe assembly includes a first die having a surface that defines a mounting plane, a first leadframe stacked over and attached to the first die, a second die stacked over and attached to the first leadframe; and a second leadframe stacked over and attached to the second die. The leadframes have die paddles with extended side panels that have attachment surfaces in the mounting plane.

BACKGROUND

1. Field

The present disclosure generally relates to integrated circuit (IC)packages and, more particularly, to leadframes and method ofmanufacturing leadframes for use in IC packages.

2. Description of the Related Art

The silicon chips on which integrated circuits are formed are so smallthat they are sensitive to damage and hard to handle, and many IC chipsare packaged in enclosures that protect the chips and provide largercontact leads that can be attached to circuitry on substrates such asprinted circuit boards. One common method of assembling an IC package ofthis type is to attach a “leadframe”, or “lead frame”, as a mechanicalsupport to the die during its assembly. A portion of the leadframe istrimmed off, leaving only the leads that provide the externalconnections for the finished product. A leadframe comprises a “diepaddle”, to which the die is attached, and “leads”, which provideexternal electrical connections. One method of connecting the die to theleads is by wirebonding small jumper wires from the die contacts tovarious leads. In other cases, a finger of the leadframe may overlay thedie directly and be soldered directly to the die contact. Lead framesare constructed from flat sheet metal either by stamping or etching.“Downsetting” consists of pushing the die paddle down relative to thebonding fingers in compliance with standard industry requirements. FIG.1 illustrates an example of a leadframe with a die paddle that has beendownset. FIG. 2 illustrates an IC package that has been cut away to showthe IC die and the leads that remain after the leadframe is trimmed andformed.

It is also possible to assemble a number of IC chips onto a smallsubstrate and package this assembly to form an IC device. As the numberof IC chips and single devices being integrated into a single deviceincrease, the package size grows and the amount of heat being generatedby the IC devices increases. One approach to keeping the size of theintegrated package down has been to stack IC chips, which presentschallenges in providing interconnects and heat dissipation.

SUMMARY

There is a need for a system that provides improved heat dissipation forstacked IC devices to enable the integration of larger numbers ofdevices while maintaining a minimal package size.

In certain embodiments, a stacked leadframe assembly is disclosed. Thestacked leadframe assembly includes a first die having a surface thatdefines a mounting plane, a first leadframe stacked over and attached tothe first die, a second die stacked over and attached to the firstleadframe, and a second leadframe stacked over and attached to thesecond die. The first and second leadframes have die paddles withextended side panels that have attachment surfaces lying in the mountingplane.

In certain embodiments, an integrated circuit device is disclosed. Theintegrated circuit device includes a substrate having circuitry and atleast one stacked leadframe assembly attached to the substrate. Thestacked leadframe assembly comprises a first die, a first leadframestacked over the first die, at least one second die stacked over thefirst leadframe; and at least one second leadframe stacked over thesecond die.

In certain embodiments, a method of manufacturing stacked leadframeassemblies is disclosed. The method includes the steps of placing afirst die on a carrier, placing a first leadframe over the first die andattaching the first leadframe to the first die, placing a second dieover the first leadframe and attaching the second die to the firstleadframe, and placing a second leadframe over the second die andattaching the second leadframe to the second die.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide furtherunderstanding and are incorporated in and constitute a part of thisspecification, illustrate disclosed embodiments and together with thedescription serve to explain the principles of the disclosedembodiments. In the drawings:

FIG. 1 is a perspective view of a leadframe having a downset die paddle.

FIG. 2 is cut-away illustration of an IC package showing the die and theportion of the leadframe that remains after trimming and forming.

FIG. 3A is an exploded view of an embodiment of a leadframe stackassembly according to certain aspects of the present disclosure.

FIG. 3B is a perspective view of an assembled stacked leadframe assemblyaccording to certain aspects of the present disclosure.

FIG. 4 is a cross-section of an embodiment of a leadframe stack assemblyaccording to certain aspects of the present disclosure.

FIG. 5 is a perspective view of an integrated circuit assemblyincorporating stacked leadframe assemblies according to certain aspectsof the present disclosure.

FIG. 6 is a perspective view of the integrated circuit assembly of FIG.5 with the addition of a heat sink according to certain aspects of thepresent disclosure.

FIG. 7 is a perspective view of an integrated circuit assembly of FIG. 6as a finished product after encapsulation according to certain aspectsof the present disclosure.

FIG. 8 shows a manufacturing frame configured to mount a carrier filmand IC dice according to certain aspects of the present disclosure.

FIG. 9 shows a manufacturing frame in which has been formed a pluralityof first leadframes according to certain aspects of the presentdisclosure.

FIG. 10 shows a manufacturing frame in which has been formed a pluralityof second leadframes according to certain aspects of the presentdisclosure.

FIGS. 11 and 12 illustrate two example embodiments showing electricalconnection of the dice to the leadframes according to certain aspects ofthe present disclosure.

FIG. 13 illustrate how two manufacturing frames may be configured tostack with co-planar surfaces according to certain aspects of thepresent disclosure.

DETAILED DESCRIPTION

The system and method disclosed herein describe how multiple stackingleadframes are integrated with multiple IC die to form a stackedleadframe assembly that can be handled as an assembly in the process ofpackaging IC assemblies or can be integrated onto a substrate as part ofan integrated assembly forming a more complicated single device.

In the following detailed description, numerous specific details are setforth to provide a full understanding of the present disclosure. It willbe apparent, however, to one ordinarily skilled in the art thatembodiments of the present disclosure may be practiced without some ofthe specific details. In other instances, well-known structures andtechniques have not been shown in detail so as not to obscure thedisclosure.

FIG. 3A is an exploded view of an embodiment of a leadframe stackassembly according to certain aspects of the present disclosure. Workingupwards from the bottom of the stack, an IC die 10 is overlaid with aleadframe 12. Leadframe 12 has a central section 20, called a “diepaddle”, that matches the die 10 in size and shape and, in thisembodiment, is shown as a monolithic element with extended side panelsthat extend out and down from the die paddle 20. The furthermost end ofthe side panels form support members 18 that have flat attachmentsurfaces on their undersides. In this embodiment, heat conduction is animportant attribute and so the portions of the leadframe that formconnecting members 22 are wide and continuous to provide improved heatconduction from the die paddle 20 to the support members 18. In certainembodiments, the connecting members 22 might be a single narrow elementor multiple elements.

The next element in the stack is a second IC die 14. This may be thesame type of die as die 12, or may be a different die. While it isadvantageous for die 14 to be the same size or smaller than die 12, itis possible to use a die 14 that is larger than die 12. The die paddle20 of leadframe 12 must be sized to accommodate both die 12 and die 14as they both attach to die paddle 12.

Leadframe 16 is located over die 14 with a die paddle area 26 andextended side panels similar to those of leadframe 12, having supportmembers 24 and connecting members 26. In this embodiment, the sidepanels extend in directions perpendicular to the side panels ofleadframe 12. The height of the die paddle 26 above the undersides ofthe support members 24 is determined by the total thickness of the dice10 and 14 and leadframe 12 plus any thickness of adhesive, solder,thermal compound, or other material placed between the dice and theleadframes. Additional pairs of die and leadframes (not shown) can beadded to this stack, as described further in FIG. 4.

FIG. 3B is a perspective view of an assembled stacked leadframe assemblyaccording to certain aspects of the present disclosure. The dice 10 and14 and leadframes 12 and 16 from FIG. 3A are shown here after assembly.Solder 30 is shown as extending beyond the edge of leadframe 16 afterreflow, attaching leadframe 16 to die 14. Other solder layers betweendie 10 and leadframe 12 and between leadframe 12 and die 14 are notvisible in this drawing. In certain embodiments, a thermally conductiveadhesive could be used in place of the solder. An adhesive could also beelectrically conductive or insulating depending on the design of thestack. The dimensions of leadframes 12 and 16 are, in this embodiment,such that the undersides of the support members are in the same plane asthe underside of die 10. This coplanarity allows this assembly to beattached to a substrate using solder or adhesive. In certainembodiments, the assembled stacked leadframe assembly will have goodphysical integrity and can be packaged on tape reels and placed usingautomatic equipment in a manner very similar to the packaging andplacement of IC packages.

FIG. 4 is a cross-section of an embodiment of a leadframe stack assemblyaccording to certain aspects of the present disclosure. The dice 10 and14 and the leadframes 12 and 16 from FIG. 3A are shown here in theassembled state. The extended side panels of leadframe 16, in this view,are perpendicular to the page and so the front side panel is notvisible. The die paddle of leadframe 16 is shown as the section 16 whilethe rear side panel is shown as the solid element below section 16 andbehind dice 10 and 14. In the embodiment shown in FIG. 4, an adhesive 40is shown between the die and leadframes. Adhesive 40 may be a thermallyconductive adhesive, thermal compound, solder, electrically conductiveadhesive, or other material providing the desired electrical, thermal,and structural characteristics. While the adhesive 40 is shown as havinga thickness commensurate with the thickness of the adjacent die 10 or14, the thickness of this adhesive may vary from essentially zero, inthe example of a thermal compound intended to fill irregularities in thesurface of the dice and leadframes, to a layer that may be thicker thanthe die, in the example of a material selected to provide thermal andelectrical insulation. In addition, while the adhesive is shown in thisembodiment as a single material in the three layers of adhesive 40, eachlayer may be a different material without departing from the scope ofthe claims.

FIG. 4 also discloses a third die 42 and third leadframe 44 in phantom,located above the dice 10 and 14 and leadframes 12 and 16. Layers ofmaterial 46 are shown between the die 42 and leadframes 16 and 44. Otherembodiments (not shown) include additional layers of die and leadframesadded above leadframe 44, with the extended side panels of theadditional leadframes becoming longer with each layer to, as shown inthis embodiment, reach the substrate.

FIG. 5 is a perspective view of an integrated circuit assembly 50incorporating stacked leadframe assemblies 52 and 54 according tocertain aspects of the present disclosure. The substrate 59 may be madeof a nonconductive material such as, for example, bismaleimide triazine(BT) or a metal. The stacked leadframe assemblies 52 and 54 may besoldered to plated areas (not shown) on a BT substrate or bonded with anadhesive. The choice of adhesive will depend in part upon the functionto be provided by the leadframes. If the leadframes are to conduct heataway from the IC devices, then it is advantageous for the adhesive to bethermally conductive. The leadframes can also provide electricalconnection of the IC die to the substrate, including both individualcircuits as well as power and ground connections, in which case it isadvantageous to use an electrically conductive adhesive. The IC assemblymay also include other large and small devices 56 and 58 that togetherprovide the functionality of assembly 50. Other types of attachmentmethods are possible, including mechanical fasteners, clamps, clips, andspring-loaded mechanisms that hold the stacked leadframe assemblies incontact with the substrate.

FIG. 6 is a perspective view of the integrated circuit assembly 50 ofFIG. 5 with the addition of a heat sink 62 according to certain aspectsof the present disclosure. In this embodiment of assembly 60, heat sink62 includes attachment pads 66 at a height and location to be in contactwith the top leadframe of stacked leadframe assemblies 52 and 54 as wellas attachment pads 64 at a height and location to be in contact with thetops of components 56. The attachment pads 66 and 64 are, in thisembodiment, bonded to their respective mating surfaces with anelectrically non-conductive adhesive. In certain embodiments, the heatsink may be electrically bonded to the leadframes, particularly if theleadframes are connected to the ground of the devices, and in certainembodiments, the heat sink may be held in thermal or electrical contactwith the leadframes by other means and there may be either no adhesivematerial or there may be a non-adhesive compound such as thermal greasebetween the heat sink and leadframes.

FIG. 7 is a perspective view of an integrated circuit assembly 60 ofFIG. 6 as a finished product 70 after encapsulation according to certainaspects of the present disclosure. In this embodiment, a moldingcompound 72 has been formed around the assembly 60, forming a solid bodywith contact pads 74 exposed. Certain embodiments may utilize apreformed shell in place of the molding compound. In this embodiment,the surfaces 62 of the heatsink 62 are left exposed and flush with thesurface of the molding compound 72. If the finished product 70 isconfigured such that this surface 62 is in contact with an external heatsink or substrate (not shown), heat may be conducted from the heat sink62 to the external heat sink.

FIG. 8 shows a manufacturing frame 80 configured to mount a carrier film84 and IC dice 89 according to certain aspects of the presentdisclosure. The frame material 88 is a thin sheet having an opening 82sized to assemble a plurality of stacked leadframe assemblies. The framematerial 88 has alignment features, shown as holes and slots 86 in thisembodiment, for mounting and aligning this frame in a manufacturingstand or jig. In this embodiment, a sheet of plastic film 84 is attachedto the back of frame material 88 across a portion of the height of theframe opening 82 as shown. As can be seen, a clear space is left at thetop (in this view) of opening 82, the benefit of which will be discussedbelow. The film 84 has an adhesive coating (not shown) on the sidefacing the frame. This front face of film 84 is equivalent to themounting surface of the finished stacked leadframe assembly. Dice 89have been placed on the film 84 and are retained in position by theadhesive coating.

FIG. 9 shows a manufacturing frame 90 in which has been formed aplurality of first leadframes 98 according to certain aspects of thepresent disclosure. The locations of the individual leadframes 98correspond to the locations of the die 89 shown in FIG. 8. Theleadframes 98 are connected to each other and the perimeter of opening94 via support structures 99 that will be removed when the stackedleadframe assemblies are separated at the end of the assembly process.The external perimeter 92 of frame 90 is sized and shaped to fit, inthis example, into the opening 82 of frame 80. When frame 90 is placedin opening 82, alignment features 96 will be located in the area notcovered by film 84, improving the accuracy of alignment of frame 90without requiring a secondary operation to remove film 84 in the area ofalignment feature 96. The attachment surfaces of leadframes 98 will bein contact with the film 84.

FIG. 10 shows a manufacturing frame 100 in which has been formed aplurality of second leadframes 108 according to certain aspects of thepresent disclosure. The leadframes 108 are connected to each other andthe edge of opening 104 via support structures 109 that will be removedwhen the stacked leadframe assemblies are separated at the end of theassembly process. These support structures 109 are formed such that theymay overlay support structures 99 while still allowing the leadframes108 to maintain their proper position in the stack. The outsideperimeter 102 may be sized and shaped to fit within the opening 94 offrame 90 or may overlay frame 90. Alignment features 106 are positionedsuch that they will overlie the area of opening 82 in frame 80 that isnot covered by film 84. In this example, the extended side panels ofleadframes 108 extend in a direction substantially perpendicular to theside panels of leadframes 98. The attachment surfaces of leadframes 108are in contact with film 84.

An example manufacturing process is described herein. It will be obviousto those of ordinary skill in the art that there are numerous variationsin the details of each step and in the order of the steps that can beimplemented without departing from the claims. An adhesive-coated film84 is placed across the opening 82 of frame 80 as shown in FIG. 8. Frame80 is attached to a reference jig in a “pick & place” machine whichplaces dice 89 at specific locations on film 84, where the adhesiveholds the die in place. A quantity of adhesive (not shown in thefigures) is placed on the top of each dice. Frame 90 is then placed overframe 80 and aligned using features 96. The underside of leadframes 98will be in contact with the top surfaces of dice 89. A quantity ofadhesive is placed on the top surface of the die paddles of leadframes98. A second set of dice (not shown in these figures) will be placed oneach of leadframes 98, with a quantity of adhesive placed on the top ofeach of this second set of dice. Frame 100 is then placed over frame 90and aligned using features 106. The underside of leadframes 108 will bein contact with the tops of the second set of dice.

This stacked set of frames 80, 90, and 100 is processed to cure theadhesive and the stacked leadframe assemblies are then separated. If theadhesive of the process described herein was solder paste, then thecuring processing would be reflowing the solder in a controlledtemperature oven. Alternately, the adhesive might include a catalyst andself-cure over a certain period of time. After separation, theindividual leadframe assemblies may be placed on a tape reel (not shown)in a manner analogous to the handling of other IC devices, placed intrays, or otherwise packaged for handling and transfer to other assemblyprocesses.

FIGS. 11 and 12 illustrate two example embodiments showing electricalconnection of the dice to the leadframes according to certain aspects ofthe present disclosure. FIG. 11 shows a stacked leadframe assembly priorto separation from the manufacturing frames wherein the top leadframehas a separate element 110 in direct electrical contact with a portionof the top die. This may provide an electrical circuit connection in thefinal assembly.

FIG. 11 also illustrates how a dam bar is formed by the combination ofthe three manufacturing frames. The outer manufacturing frame comprises,in the view of FIG. 11, sections 112 and 116 having shaped notches 113and 117, respectively. This pattern is repeated on the other side ofthis die location, visible in the view of FIG. 11, and at all other dielocations (not shown) within the frame. The second frame had a partialbar dam 114 formed across the leads, wherein the partial dam bar 114 hasa shaped tip at one end that fits into shaped notch 113 and a flatsurface, in this example, at the other end of dam bar 114. The thirdframe has a partial dam bar 115 that also has a shaped tip at one endthat engages with shaped notch 117 and a flat surface, in this example,at the other end that abuts the flat surface of partial dam bar 114. Itwill be apparent to those of skill in the art that other shapes of thetip and notch and of the abutting surfaces are possible. The abuttingpartial dam bars 114 and 117 on each side of the die location and theportions 112 and 116 of the first frame form a continuous perimeteraround the die location. This continuous perimeter forms a dam for theovermolding of the stacked leadframe with molding compound. Theovermolding step is accomplished by clamping this layered assembly offrames between shaped injection molding cavities (not shown) which sealagainst this perimeter of first frame section 112 and 116 and partialdam bars 114 and 115, forming a cavity around the stacked leadframe. Themolding compound is injected through the area of notch 118, filling theopen space within the perimeter of the dam bar. The dam bar prevents themolding compound from flowing into the area 119 without requiring theinjection molding cavities to be shaped to conform to the openings inthe frames. This minimizes encapsulation bleed during the overmoldingprocess.

FIG. 12 shows a pair of stacked leadframe assemblies intended to be usedas a pair, wherein the first leadframes of the stacked leadframeassemblies have a common circuit lead 120 which, in the final assembly,could provide a circuit function such as connection to an H-bridge motorcontroller.

FIG. 13 illustrate how two manufacturing frames may be configured tostack with co-planar surfaces according to certain aspects of thepresent disclosure. In this example, an outer manufacturing frame 130carries a plurality of first leadframes 132 which are connected to theouter manufacturing frame by bridge sections 134 that have been etchedfrom the top, as seen in this view, to approximately half the originalthickness. An inner manufacturing frame 136 carries a plurality ofsecond leadframes 138 that are offset to fit over leadframes 132. Theouter perimeter of inner manufacturing frame 136 has bridge sections 140that cross over the bridge sections 134, where the bridge sections 140have been etched from the bottom, in this view, to approximately halfthe original thickness. As both bridge sections 134 and 140 have beenetched in opposite relative directions over coincident areas, formingmatching notches across the coincident area, bridge section 140 overlaysbridge section 134 and allows the inner manufacturing frame 136 to lieon a common plane with outer manufacturing frame 130. Positioning boththe inner and outer manufacturing frames 136 and 130 to a common planarsurface simplifies the manufacturing process.

It can be seen that the disclosed embodiments of the stacked leadframeassembly provide improved thermal and electrical connection of multiplestacked dice to a substrate. Enabling the use of stacked dice,especially for IC die such as high-power switching transistors thatgenerate a large amount of heat, reduces the size of the total assemblywhile maintaining the junctions of the IC dice at temperatures that willprovide a long, reliable operating life. These stacked leadframeassemblies can be assembled and then handled like other IC devices,reducing the impact of using these types of devices with existingequipment and processes.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. While theforegoing has described what are considered to be the best mode and/orother examples, it is understood that various modifications to theseaspects will be readily apparent to those skilled in the art, and thegeneric principles defined herein may be applied to other aspects. Thus,the claims are not intended to be limited to the aspects shown herein,but is to be accorded the full scope consistent with the languageclaims, wherein reference to an element in the singular is not intendedto mean “one and only one” unless specifically so stated, but rather“one or more.” Unless specifically stated otherwise, the term “some”refers to one or more. Pronouns in the masculine (e.g., his) include thefeminine and neuter gender (e.g., her and its) and vice versa. Headingsand subheadings, if any, are used for convenience only and do not limitthe invention.

It is understood that the specific order or hierarchy of steps in theprocesses disclosed is an illustration of exemplary approaches. Basedupon design preferences, it is understood that the specific order orhierarchy of steps in the processes may be rearranged. Some of the stepsmay be performed simultaneously. The accompanying method claims presentelements of the various steps in a sample order, and are not meant to belimited to the specific order or hierarchy presented.

Terms such as “top,” “bottom,” “front,” “rear” and the like as used inthis disclosure should be understood as referring to an arbitrary frameof reference, rather than to the ordinary gravitational frame ofreference. Thus, a top surface, a bottom surface, a front surface, and arear surface may extend upwardly, downwardly, diagonally, orhorizontally in a gravitational frame of reference.

A phrase such as an “aspect” does not imply that such aspect isessential to the subject technology or that such aspect applies to allconfigurations of the subject technology. A disclosure relating to anaspect may apply to all configurations, or one or more configurations. Aphrase such as an aspect may refer to one or more aspects and viceversa. A phrase such as an “embodiment” does not imply that suchembodiment is essential to the subject technology or that suchembodiment applies to all configurations of the subject technology. Adisclosure relating to an embodiment may apply to all embodiments, orone or more embodiments. A phrase such an embodiment may refer to one ormore embodiments and vice versa.

The word “exemplary” is used herein to mean “serving as an example orillustration.” Any aspect or design described herein as “exemplary” isnot necessarily to be construed as preferred or advantageous over otheraspects or designs.

All structural and functional equivalents to the elements of the variousaspects described throughout this disclosure that are known or latercome to be known to those of ordinary skill in the art are expresslyincorporated herein by reference and are intended to be encompassed bythe claims. Moreover, nothing disclosed herein is intended to bededicated to the public regardless of whether such disclosure isexplicitly recited in the claims. No claim element is to be construedunder the provisions of 35 U.S.C. §112, sixth paragraph, unless theelement is expressly recited using the phrase “means for” or, in thecase of a method claim, the element is recited using the phrase “stepfor.” Furthermore, to the extent that the term “include,” “have,” or thelike is used in the description or the claims, such term is intended tobe inclusive in a manner similar to the term “comprise” as “comprise” isinterpreted when employed as a transitional word in a claim.

What is claimed is:
 1. A stacked leadframe assembly comprising: a firstdie having a surface that defines a mounting plane; a first leadframehaving a die paddle with side panels that extend in a first directionand have attachment surfaces in the mounting plane, the first leadframebeing stacked over and attached to the first die; a second die, stackedover and attached to the first leadframe; and a second leadframe havinga die paddle with side panels that extend in a second direction that isat an angle in the range of 45-135° from the first direction and haveattachment surfaces in the mounting plane, the second leadframe beingstacked over and attached to the second die, wherein the leadframeassembly is configured so as to allow direct attachment of the surfaceof the first die to a substrate.
 2. The leadframe assembly of claim 1wherein at least one of the leadframes is thermally connected to atleast one of the dice.
 3. The leadframe assembly of claim 1 wherein: thefirst leadframe is connected to a first manufacturing frame by a firstbridge section; the second leadframe is connected to a secondmanufacturing frame by a second bridge section; the first leadframecomprises a first top surface; the second leadframe comprises a secondtop surface; the first and second leadframes both comprise a firstthickness; the first bridge section comprises a second thickness that isless than the first thickness; the second bridge section comprises athird thickness that is less than the difference between the first andsecond thicknesses; and the first and second bridge sections at leastpartially overlap each other such that the first top surface is coplanarwith the second top surface when the second manufacturing frame isstacked over the first manufacturing frame.
 4. The leadframe assembly ofclaim 1 wherein at least one of the leadframes is electrically isolatedfrom the dice.
 5. The leadframe assembly of claim 1 wherein the die andleadframes are attached to each other by solder.
 6. The leadframeassembly of claim 1 wherein the die and leadframes are attached to eachother by thermally conductive adhesive.
 7. The stackable leadframeassembly of claim 1 wherein the directions in which the side panelsextend from the first and second leadframes are perpendicular to eachother.
 8. The leadframe assembly of claim 1 wherein each leadframecomprises: first and second support members each having an attachmentsurface, the attachment surfaces lying in the mounting plane; a diepaddle that is substantially planar with a thickness and a bottomsurface, the bottom surface lying in a second plane that issubstantially parallel to the mounting plane and offset from themounting plane by a distance that is approximately equal to the totalthickness of the dice and leadframes that are located under theleadframe, the die paddle having first and second ends on opposite sidesof the die paddle; at least one first connecting member connectedbetween the first end of the die paddle and the first support member;and at least one second connecting member connected between the secondend of the die paddle and the second support member.
 9. The leadframeassembly of claim 1 further comprising at least a third die and at leasta third leadframe stacked over and attached to the stack of dice andleadframes.
 10. An integrated circuit device, comprising: a substratehaving circuitry; at least one stacked leadframe assembly attached tothe substrate, the stacked leadframe assembly comprising: a first diehaving a surface directly attached to the circuitry of the substrate,the surface defining a mounting plane; a first leadframe stacked overthe first die, the first leadframe comprising attachment surfacescoplanar with the mounting plane; at least one second die stacked overthe first leadframe; and at least one second leadframe stacked over thesecond die, the at least one second leadframe comprising attachmentsurfaces coplanar with the mounting plane; and an enclosing body thatencapsulates the substrate and stacked leadframe assembly, wherein theattachment surfaces that are coplanar with the mounting plane are theonly portions of the first and at least one second leadframes that areexposed through the enclosing body.
 11. The integrated circuit device ofclaim 10 wherein the stacked leadframe assembly is attached to thesubstrate with solder.
 12. The integrated circuit device of claim 10wherein a portion of at least one of the leadframes provides anelectrical connection from at least one of the die in the stackedleadframe assembly to the circuitry on the substrate.
 13. The integratedcircuit device of claim 10 wherein at least one of the leadframesprovides a thermal connection from at least one of the die in thestacked leadframe assembly to the substrate.
 14. The integrated circuitdevice of claim 10 further comprising a heatsink in thermal contact withthe stacked leadframe assembly, wherein a portion of the heatsink isexposed on an external surface of the body.
 15. The integrated circuitdevice of claim 14 wherein the enclosing body is cut from a stackcomprising a first and at least one second manufacturing frames that areovermolded with a molding compound, wherein the first and at least onesecond manufacturing frames are configured to lie in a single planealong and have a constant combined thickness around a perimeter of thestack of manufacturing frames when the molding compound is injectedaround the stack of manufacturing frames.